The major objective of this project is the elucidation of genetically controlled host defense mechanisms involved in recovery from virus-induced leukemia in mice. Three new genes which influence recovery from established Friend virus leukemia have been identified. Two genes are located within the major histocompatibility complex (H-2), and one is a non-H-2 gene whose location is unknown at present. Attempts are now being made to understand the mechanisms of action of these genes in terms of their influence on various defense mechanisms necessary for elimination of the neoplastic cells and control of leukemia virus infection. Transplantable cell lines derived from virus-induced leukemic organs have been established as models of homogeneous leukemia cell populations. Cellular origin of these leukemia cells has been examined by characterization of cell surface antigenic markers and receptors. Production of intact virus as well as viral antigens has been studied in these cell lines to gain an understanding of the virus-induced cellular membrane antigens involved in specific immune recognition and elimination of leukemia cells. BIBLIOGRAPHIC REFERENCES: Chesebro, B., Wehrly, K., Chesebro, K., and Portis, J.: Characterization of Ia8 antigen, Thy-1.2 antigen, complement receptors, and virus production in a group of murine virus-induced leukemia cell lines. J. Immunol. 117: 1267-1274, 1976.